We continue our development of carbon monoxide (CO)-monitoring technology for laboratory and bedside diagnosis of hemolysis or increased total bilirubin production from other causes. This involves developing and refining instrumentation and techniques for the measurement of excreted CO. These efforts, in cooperation with Natus Medical, Inc. of San Carlos, CA, have resulted in the production of a portable, non-invasive instrument for the bedside monitoring of end- tidal breath CO as an index of bilirubin production for all causes. We evaluated this instrument, formerly known as Baby's Breath, with a CO measuring efficacy of 96%, with neonates in 1996. Recently, the instrument renamed CO-Stat, has been evaluated in a population ranging in age from neonates to adults.